Inverter Power Supply Circuit With Backup Branch Fault Isolation
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Solution Overview
Problem
Existing power supply circuits in inverters for electric vehicles face challenges in ensuring a safe state during emergencies or faults, particularly when high-voltage and low-voltage branches fail, leading to potential hazards and system instability.
Innovation Solution
A power supply circuit with three branches: high-voltage, low-voltage, and backup supply, using separate DC/DC converters and safety disconnection circuits to ensure continuous power to critical components, even in fault conditions, and a safety control device to initiate a safe state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single power supply circuit is used in the inverter, then the device complexity is reduced, but the functional safety and reliability during faults are insufficient
Solution Approach 1:
The power supply circuit is segmented into three independent branches: high-voltage branch, low-voltage branch, and backup supply branch. Each branch can operate independently to supply power to different consumers, ensuring that a fault in one branch does not affect the others. This segmentation enables the system to maintain functional safety by isolating faults while preserving power supply to critical components.
Solution Approach 2:
Different branches are assigned different voltage levels and functional roles tailored to specific consumer requirements. The high-voltage branch supplies power requiring high voltage, the low-voltage branch supplies low-voltage consumers, and the backup supply branch provides redundant power. This local differentiation optimizes the power supply quality for each consumer while maintaining overall system reliability.
2Reliability
If DC/DC converters are used to connect power branches, then power conversion and isolation are achieved, but the device complexity and component requirements increase
Solution Approach 1:
The power conversion function is segmented across multiple DC/DC converters, with each converter dedicated to a specific branch connection. The first DC/DC converter connects the high-voltage branch to the low-voltage branch, while the second DC/DC converter connects the high-voltage branch to the backup supply branch. This segmentation provides electrical isolation and independent power conversion paths, enhancing reliability while distributing the complexity across modular components.
3Reliability
If redundancy is increased to prevent faults, then the functional safety is improved, but the cost and component requirements increase
Solution Approach 1:
The backup supply branch is designed to recover and utilize power from the high-voltage branch through the second DC/DC converter when the low-voltage branch fails. This allows the system to discard the faulty low-voltage supply path and recover power supply functionality through the backup branch, maintaining operational continuity without requiring completely redundant independent power sources for all consumers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances functional safety by maintaining a safe operational state during faults, reducing component damage and ensuring reliable operation of the inverter system, particularly in high-voltage environments.
Implementation Method 1
The high-voltage branch is connected to the low-voltage branch via a DC/DC converter, and the high-voltage branch is connected to the backup supply branch via a backup supply DC/DC converter
Data Source
AI summary
A power supply circuit in an inverter for driving an electrical machine includes a high-voltage branch, a low-voltage branch, a backup supply branch, an operating DC/DC converter, which is connected on the one hand to the high-voltage branch and on the other hand to the low-voltage branch, a backup supply DC/DC converter, which is connected on the one hand to the high-voltage branch and on the other hand to the backup supply branch, an inverter circuit for connecting the electrical machine to the high-voltage branch, and a safety control device which is set up to switch the inverter circuit to a safe state when a shutdown situation is present, wherein the inverter circuit and the safety control device are supplied with energy from the low-voltage branch, wherein the inverter circuit and the safety control device are additionally supplied or can be supplied with energy from the backup supply branch.